In cellular phosphorylation assays, GSK1838705A potently inhibits IGF-IR and insulin receptor phosphorylation with IC50s of 85 and 79 nM, respectively. appKi values are 0.7 nM for IGF-IR and 1.1 nM for insulin receptor using the filter binding assay. GSK1838705A inhibits the proliferation in a panel of cell lines derived from solid and hematologic tumors. The EC50s of GSK1838705A range from 20 nM to >8 μM, but are <1 μM in most multiple myeloma and Ewing's sarcoma cell lines[1].

Baculovirus-expressed glutathione S-transferase–tagged proteins encoding the intracellular domain of IGF-IR (amino acids 957–1367) and IR (amino acids 979–1382) are used for determinations of IC50s by a homogeneous time-resolved fluorescence assay. A filter binding assay is used for appKi determinations using activated IGF-IR and IR kinases. Expanded kinase-selectivity profiling of GSK1838705A is carried out by screening the compound in the KinaseProfiler panel[1]. MCE has not independently confirmed the accuracy of these methods. They are for reference only.

Cells are seeded in 96-well dishes, incubated overnight at 37°C, and treated with DMSO or GSK1838705A for 72 h. For the NIH-3T3/LISN proliferation assays, cells are seeded on collagen-coated 96-well tissue culture plates and allowed to adhere for 24 h. The medium is replaced with serum-free medium and the cells are treated with GSK1838705A for 2 h. Cells are incubated for 72 h after addition of IGF-I (30 ng/mL). Cell proliferation is quantified using the CellTiter-Glo Luminescent Cell Viability Assay. IC50s are determined from cytotoxicity curves using a four-parameter curve fit software package[1]. MCE has not independently confirmed the accuracy of these methods. They are for reference only.

Mice: Exponentially growing cells are implanted s.c. into the right flank of 8- to 12-wk-old female nu/nu CD-1 or SCID mice. Mice are dosed p.o. with the formulating vehicle or GSK1838705A. Mice are weighed and tumors measured by calipers twice weekly. Tumor volumes are calculated[1] MCE has not independently confirmed the accuracy of these methods. They are for reference only.